The preparation and biological evaluation of analogs of the Antitumor Natural Product Camptothecin are under investigation. Particular emphasis is directed toward analogs in which the A-ring, B- ring and the quinoline nitrogen have been deleted. Studies pursuant to the synthesis of the antitumor sesquiterpene vernolepin are in progress. Strategies for constructing the ring A lactone and the angular vinyl group have been realized. Current efforts are directed primarily toward construction of the C-ring lactone. The total syntheses of steroids and triterpenes are under intense investigation. We have now reached the point of synthesizing estrone in chirally specific form. The total synthesis of lanosterol appears to be a feasible objective within the coming year. The applications of activated cyclopropanes to the synthesis of complex Natural Products are being investigated. Routes to pyrrolizidines, indolizidines, furylidines and fused carbocycles have been developed.